1. Field of Technology
Embodiments disclosed herein relate to light emitting diode (LED) lighting systems, and more specifically to adjusting the output light intensity and color temperature of dimmable LED lamps.
2. Description of the Related Art
LEDs are being adopted in a wide variety of electronics applications, for example, architectural lighting, automotive head and tail lights, backlights for liquid crystal display devices, flashlights, etc. Compared to conventional lighting source such as incandescent lamps and fluorescent lamps, LEDs have significant advantages, including higher efficiency, better directionality, better color stability, higher reliability, longer life, and smaller size.
Today, there are many LED based lamps available that are designed to be direct replacement of incandescent bulbs and can be dimmed by a dimmer switch. When incandescent bulbs are dimmed, the filament temperature decreases, causing the emitted light to appear warmer as its color temperature changes from white, to yellow, and then finally to orange. On the other hand, LEDs typically do not change color temperature as they are dimmed and produce the same color light (e.g. white light) even when the light intensity is decreased. Some conventional LED lamps attempt to mimic the light output of incandescent bulbs by mixing different color LEDs and adjusting the brightness of the different colors as the dimming level increases. However, these conventional LED lamps use complex circuitry for controlling different LED colors, which results in LED lamps that are expensive to produce, are prone to failure, and are not commercially viable.